P. Prati

Instrumental indices for upper limb function assessment in stroke patients: a validation study

BackgroundRobotic exoskeletons are increasingly being used in objective and quantitative assessment of upper limb (UL) movements. A set of instrumental indices computed during robot-assisted reaching tasks with the Armeo®Spring has been proven to assess UL functionality. The aim of this study was to test the construct validity of this indices-based UL assessment when used with patients who have had a stroke.MethodsForty-four 45- to 79-year-old stroke patients with a Wolf Motor Function Test ability score (WMFT-FAS) ranging from 10 to 75 and a Motricity Index (MI) ranging from 14 to 33 at shoulder and elbow were enrolled, thus covering a wide range of impairments. Residual UL function was assessed by both the WMFT-FAS and the WMFT-TIME, as well as by a set of 9 numerical indices assessing movement accuracy, velocity and smoothness computed from a 3D endpoint trajectory obtained during the “Vertical Capture” task of the Armeo®Spring device. To explore which variables better represented motor control deficits, the Mann-Whitney U Test was used to compare patients’ indices to those obtained from 25 healthy individuals. To explore the inner relationships between indices and construct validity in assessing accuracy, velocity and smoothness, a factor analysis was carried out. To verify the indices concurrent validity, they were compared to both WMFT-FAS and WMFT-TIME by the Spearman’s correlation coefficient.ResultsSeven indices of stroke subjects were significantly different from those of healthy controls, with effect sizes in the range 0.35–0.74. Factor analysis confirmed that specific subsets of indices belonged to the domains of accuracy, velocity and smoothness (discriminant validity). One accuracy index, both velocity indices and two smoothness indices were significantly correlated with WMFT-FAS and WMFT-TIME (|rho| = 0.31–0.50) (concurrent validity). One index for each of the assessed movement domains was proven to have construct validity (discriminant and concurrent) and was selected. Moreover, the indices were able to detect differences in accuracy, velocity and/or smoothness in patients with the same WMFT level.ConclusionsThe proposed index-based UL assessment can be used to integrate and support clinical evaluation of UL function in stroke patients.

Age explains limited hip extension recovery at one year from total hip arthroplasty

BACKGROUND To investigate the dependency of the one-year recovery in gait after total hip arthroplasty on age and preoperative conditions. METHODS Longitudinal retrospective study on 20 elderly patients with unilateral total hip arthroplasty consequent to hip osteoarthritis, assessed by gait analysis before surgery (T0), 2weeks (T1), 6 (T2) and 12months (T3) post-surgery. A set of variables assessing primary gait deviations and compensatory mechanisms were extracted from gait analysis data. Their variations throughout the one-year period were analyzed through a repeated measures ANOVA. Their dependency on preoperative conditions (age, hip passive limitations and Thomas Test) at one year after surgery were assessed through a correlation analysis and an ANCOVA. FINDINGS Hip sagittal range significantly increased (P<0.05) after each measurement session from mean 21 (SD 10) degrees at T0, to 31 (6) at T1, to 34 (6) at T2 until 36 (4) degrees at T3. The peak of hip and ankle power generation significantly increased from T0 to T3, with a progressive reduction of compensatory mechanisms towards normal values. At T3, preoperative hip passive extension and Thomas Test score did not affect hip sagittal range during gait, while age did (P<0.05, R2=0.36). Ankle and hip peak powers were also correlated with age (P=0.033 and P=0.008, respectively). In our sample, age was the main cause of hip sagittal joint range limitation. INTERPRETATION At one year from total hip arthroplasty, age affects hip joint limitations and gait recovery more than preoperative passive restrictions due to muscle shortening.

Electromyographic activity of the vastus intermedius muscle in patients with stiff-knee gait after stroke. A retrospective observational study

Stiff-knee gait (SKG) in hemiplegic patients is often due to an inappropriate activity of the quadriceps femoris. However, there are no studies in literature addressing the vastus intermedius (VI) involvement in SKG. In this study, VI activity was analyzed in a sample of 46 chronic stroke patients with SKG, during spontaneous gait. VI activity was recorded by fine-wire electrodes inserted under ultrasound guidance then confirmed by electrical stimulation. The measured VI activity was compared to the normal reference pattern reported in literature and classified (e.g. premature, prolonged). The occurrences of abnormal activations during each sub-phase of the gait cycle were assessed. VI activity presented an abnormal timing in 96% of the sample. The most common pathological pattern (in 46% of the sample) was the combination of premature and prolonged VI activation. Nearly 20% of patients presented a continuous activity. A pathological activation in patients was found for 91% in mid stance, for more than 50% in terminal stance and pre-swing and for 37% and 70% in initial- and mid-swing. Results indicate that abnormal VI activity is frequent in patients with SKG. Hence, VI activity should be included in the assessment of SKG to assist in the clinical decision-making processes.